WARNING: This product contains Glycolic Acid. Because sensitivity to Glycolic Acid varies substantially from person to person, we STRONGLY RECOMMEND to always test the product on a small area before using it. In order to test, apply a small quantity of product on a very limited, dime-sized area behind the ear or under the chin, and wait for 2 to 3 minutes. ALWAYS read and follow the instructions available online as specified on the product label BEFORE using the product.